Somehow I have got in a situation where whenever I use PayPal to pay for something it sends me a message on Facebook. I want to cancel my PayPal account and my Facebook account but before I would do so, I figured there would be a way to fix it. However, the web doesn't seem to offer any help.

However, when I got to the relevant page in Facebook there was nothing labeled PayPal. There was one payment method with an icon that was a triangle over three vertical bars over a horizontal bar. No idea if that is PayPal, no tooltips or other information. However, I clicked Remove anyway and got a message saying "Sorry we were unable to remove your payment method. Please try again later."

Some other third-party that's bridging the two? I seem to recall there was a social app that would broadcast your purchases. Some sort of self-control booster. (Unfortunately, the name escapes me.) I'd check to ensure that the apps you have connected to your PayPal and Facebook accounts are ones you really want to have.
– aleFeb 9 '17 at 16:29